This invention relates to an interruption informing circuit arrangement for use in a virtual machine in informing an active operating system of a held interruption which is an interruption sent from an input/output (I/O) device and is held in the interruption informing circuit arrangement.
The virtual machine is operable as a plurality of operating systems which are controlled by a control program. The operating systems include interruption processing programs, respectively.
In such a virtual machine, a particular processing must be carried out when an interruption request is sent from the I/O device. For example, an interruption request which is received during operation of a particular one of the operating systems may be directed to another of the operating systems that should be interrupted. Therefore, any interruption request must access the control program in order that the control program can judge which one of the operating systems should be interrupted by the interruption request as a judged operating system and that the control program can start the interruption processing program of the judged operating system. The judged operating system may, however, not be able to receive the interruption request at this time.
In such a case, the control program of a conventional virtual machine informs the judged operating system of the fact that the interruption request is pending. The control program is started when the interruption request can be received during operation of the judged operating system. Such a method is disclosed in an article contributed by R. P. Parmelee et al to IBM Systems Journal, Volume 11 (1972), No. 2, pages 99 to 131, under the title of "Virtual storage and virtual machine concepts."
However, this method is disadvantageous in that the overhead of processing by the control program increases because the control program waits to process the interruption request until the interruption request can be received.